The present invention relates to the field of angioplasty. In particular, the present invention relates to a balloon catheter which provides prolonged dilatations of coronary arteries without blocking blood flow by utilizing passive perfusion.
Angioplasty has gained wide acceptance as an efficient, effective and alternative method of removing undesirous restrictions caused by tissue growth or lesions on the inner walls of the blood vessels. Such tissue growth or lesions cause a narrowing of the blood vessels called a "stenosis" which severely restricts or limits the flow of blood. In the most widely used form of angioplasty, a dilatation catheter, which has an inflatable balloon at its distal end, is guided through the vascular system. With the aid of fluoroscopy, a physician is able to position the balloon across the stenosis. The balloon is then inflated by applying fluid pressure through an inflation lumen of the catheter to the balloon. Inflation of the balloon stretches the artery and presses the stenosis-causing lesion into the artery wall to remove the constriction and re-establish acceptable blood flow through the artery.
One disadvantage of many dilatation catheters of the prior art is the complete occlusion of the blood vessel that results while the balloon is inflated. Prolonged complete blockage of a coronary artery poses serious risk of damage to the tissue downstream from the occlusion which is deprived of oxygenated blood. This consequence poses a severe limitation on the length of time the balloon can remain expanded within an artery to effectively remove the stenosis. Longer inflation times increase the probability that the artery will remain open after the catheter is removed.
Various methods for providing passive perfusion of blood through or past the inflated balloon are found in the following prior art references: Baran et al. U.S. Pat. No. 4,423,725; Sahota U.S. Pat. No. 4,581,017; Hershenson U.S. Pat. No. 4,585,000; Horzewski et al. U.S. Pat. No. 4,771,777; Mueller et al. U.S. Pat. No. 4,790,315; Songer et al. U.S. Pat. No. 4,892,519; Goldberger U.S. Pat. No. 4,909,252; Sogard et al. U.S. Pat. No. 4,944,745; Sahota U.S. Pat. No. 4,983,167 and European Patent Application 0 246 998; Boussignac et al. U.S. Pat. No. 5,000,734; Patel U.S. Pat. No. 5,000,743; and Bonzel U.S. Pat. No. 5,002,531.
There is still a need in the field, however, for a perfusion dilatation catheter with an optimal perfusion cavity which permits good arterial blood flow during a dilatation procedure, and is capable of being manufactured with relative ease and minimal cost.